Example embodiments of the present invention relate to a magnetometer, and in particular to a magnetometer that detects a magnetic field by optically pumping a gas and detecting an optical modulation of the gas.
The magnetic field is a fundamental physical quantity, and its precise measurement plays a central role in addressing the scientific objectives of many planetary, solar, and interplanetary science missions, as well as the practical objectives of commercial and consumer electronics. Fluxgate magnetometers are widely used because they measure the vector magnetic field with good sensitivity and require only modest mass and power resources. Because fluxgate magnetometers measure voltages proportional to the ambient magnetic field, their scale factors and offsets must be calibrated and are subject to drift over time and temperature.
On the other hand, the measurement technique of proton-precession and optically-pumped magnetometers is based on fundamental physical quantities such as the magnetic moment and spin angular momentum of the electrons and atomic nuclei. While the operating principle of proton-precession magnetometers is based on nuclear magnetic resonance, optically-pumped magnetometers are based on the precession of electron spins as the mechanism for magnetic field detection. Both types of atomic magnetometers have demonstrated excellent performance with respect to sensitivity, absolute accuracy, and dynamic range while providing long-term absolute accuracy and stability. However, a major disadvantage of these instruments is their significant mass and high power requirements. With sensors as large as 1500 cm3, these instruments can draw up to tens of Watts of power and have a typical mass of several kilograms. In addition, because the atomic resonances sensed by these instruments do not provide directional magnetic field information, vector measurement capability, which is required by most space-based scientific missions, must either be retrofitted or obtained in combination with a fluxgate magnetometer.